Strand treatment



Aug. 26, 1969 K. STANLEY 3,462,314

STRAND TREATMENT Filed on. 26, 1967 s Sheets-Sheet 1 7 INVENTOR. 77 6 Roam? /r. srmvzr I BY/7 WWE v ATTOK VEZQ w Ill e 67 I H" R. K. STANLEY STRAND TREATMENT I #ZwL Aug. 26, 1969 Filed Oct. 26, 1967 INVENTOR. 05597 K. JM/Vlf) BY H fizz/ 1) MS A Tram/H15 Aug. 26, 1969 K. STANLEY 3,462,314

I STRAND TREATMENT Filed Oct. 26, 1967 I 5 Sheets5heet z INVENTOR. 805E197 K STA/VA BY Mug/ as [Jury ATTOK/VEYJ United States Patent 015cc 3,462,814 Patented Aug. 26, 1969 US. Cl. 28-7214 12 Claims ABSTRACT OF THE DISCLOSURE This invention relates to treatment of textile strands, concerning especially crimping thereof by successive extension and compression along the strand axis. In particular, such strands are drawn to increased length and then are stutfer crimped. The drawn strands are preferably underfed to the stutter crimper and often are drawn further at the input thereto.

This is a continuation-in-part of my copending patent application Ser. No. 302,758 filed July 31, 1963, now US. Patent 3,376,622, granted Apr. 9, 1968.

Textile strands can be produced by extrusion of fiberforming compositions through spinneret orifices and collection of the resulting filaments or fibers. Many polymeric fiber-forming compositions so treated produce strands of relatively low tensile strength because of relatively low macromolecular orientation with respect to the longitudinal axis. In most such compositions the orientation and tensile strength can be increased readily because the strand components (usually continuous filaments) are drawable to an attenuated and extended condition of high orientation from which there is little or no tendency to return to the original condition. Nylon strands, for example, can be drawn so readily at room temperature that they are commonly indicated as being cold-drawable. The strand temperature normally increases during drawing because of intermolecular friction and friction with any snubbing pin or similar means employed to restrict the drawing location. In actual practice the strand, regardless of composition, may 'be heated to facilitate and to localize the drawing operation.

Strands of continuous filaments, whether oriented or unoriented, are inappropriate for many uses because of their rectilinearity, which is conducive to slickness, translucency, and low bulk, all of which can be eliminated or modified by any of a variety of processes usually called crimping or texturing. Nearly all of those processes (e.g., edge-crimping, gear-crimping, jet-crimping, and twist-crimping) tend to extend the strand axially while deforming it transversely of the longitudinal axis and, therefore, may be expected to be compatible with an immediate pre-drawing operation. StuiIer-crimping, however, which alters the configuration of and incidentally heats the strands by longitudinal compression thereof, may be expected to be separated from the drawing process in location or time (except for such drawing being prior, usually long prior) rather than adapted to follow immediately upon an attenuation of the strand to increased length. Because of the tendency of the drawn strands to retract somewhat it has been thought desirable in some attempts to stuffer crimp recently drawn strands to overfeed them to the crimper and thereby avoid undue tension therein. In general, attempts to crimp thermoplastic textile strands within a short time following drawing thereof have required that the strands be heated or wet during both steps or both heated and wet during one or both steps. There is a considerable need for improved apparatus, technique, and results.

A primary object of the present invention is provision of a novel drawing and crimping process for textile strands.

Another object is crimping of textile strands by com pression along the strand axis immediately following permanent extension therealong.

A further object is elimination of the customary requirement that thermoplastic strands be heated or wet (or both) during drawing and crimping.

Other objects of this invention, together with means and methods for accomplishing the various objects, will be apparent from the following description and the accompanying drawings.

FIG. 1 is a schematic representation of drawing and crimping steps with intervening time period;

FIG. 2 is a schematic representation of a continuous draw-crimping process without intervening time period;

FIG. 3 is a perspective view (somewhat stylized) of a drawing system useful according to this invention;

FIG. 4 is a front elevation of a stutter-crimper for use according to this invention;

FIG. 5 is a side elevation of the stuffer-crimper of FIG. 4;

FIG. 6 is a sectional plan of the same stutter-crimper taken at VI-VI of FIG. 5;

FIG. 7 is a front elevation of a modification of apparatus according to this invention;

FIG. 8 is a front elevation of a further modification of apparatus according to this invention;

FIG. 9 is a side elevation of a length increment of monofilament textile strand in unoriented or only partly oriented condition;

FIG. 10 is a side elevation of the same increment of the strand of FIG. 9 after attenuation to increased length to orient it;

FIG. 11 is a side elevation of the oriented length increment of the strand of FIG. 10 buckling under axially compressive stress;

FIG. 12 is a side elevation of the same strand length increment crimped into a generally U-shaped configuratlon;

FIG. 13 is a side elevation (on reduced scale and somewhat stylized) of successive length increments crimped as in FIG. 12; and

FIG. 14 is a side elevation (on a much further reduced scale and also somewhat stylized (of a considerably greater length of crimped strand than shown in FIG. 13.

In general, the objects of the present invention are attained by attenuating a polymeric textile strand to increased length and immediately thereafter compressing the strand axially to buckle successive length increments thereof into crimped configuration without necessity for the strand to be heated or wet (or both). The invention comprehends particularly such process as an improvement in stutfer-crimping wherein a drawn strand to be crimped is underfed to the crimper and even is drawn at the input thereto. Certain apparatus for such drawing and immediate stuifer-crimping of textile trands comes within the purview of this invention, as indicated below.

FIG. 1 shows schematically zone 11 wherein a strand is attenuated to insreased length or drawn and zone 13 wherein the strand is crimped, as by any conventional system. Intervening zone 12, shown in broken lines and traversed by an arrow leading from zone 11 to zone 13, represents the period (conventionally excessive) of time intervening between drawing and crimping. FIG. 2 shows schematically drawing zone 15, wherein the strand is treated as in zone 11, and compressive crimping zone 16 contiguous therewith according to this invention. The

arrow indicates the passage of the strand immediately to the crimping zone from the drawing Zone without appreciable time intervening. The meaning of this limitation will be apparent from the following details of the apparatus and process of this invention.

FIG. 3 shows, in perspective (stylized by omission of supporting, heating, driving, or other elements), rolls 21, 22, and 23 at the input end of a drawing zone, useful according to this invention, and rolls 31, 32, and 33 at the output end of the zone. Located in the space between the two sets of rolls is drawn pin 27, use of which'is optional. Strand 20, whose direction of travel is indicated by arrows, proceeds generally from left to right, passing about a quadrant of roll 21, downward through the nip of rolls 21 and 22, about the lower half of roll 22, upward through the nip of rolls 22 and 23, and over a quadrant of roll 23. It then makes a single turn about drawn pin 27, after which it is denoted as 20'. After leaving the draw pin the strand proceeds about a quadrant of roll 31, downward through the nip between rolls 31 and 32, about the lower half of roll 32, and then upward through the nip between rolls 32 and 33.

It will be understood that at least one of the rolls in each of these two sets is driven by suitable motive means (not shown) and that all the rolls within each set rotate at constant speed, whether driven directly by the motive means or indirectly by contact (essentially non-slipping) with one another. The surface speed of the rolls in the second or forwarding set (31, 32, 33) is greater than the speed of the rolls in the first or input set, thereby determining the extent to which the strand is drawn therebetween. The draw pin does not rotate but is fixed so as to snub the strand passing about it. The pin may, but need not, be heated by any conventional means (e.g., electrically or by steam, preferably supplied internally) as is customary in the art of strand drawing.

With some strand compositions it may be helpful to heat one or both sets of rolls (in addition to, or instead of, the draw pin). Heating the first set of rolls preheats the strand for drawing, possibly rendering it easier to draw, and incidentally preheating it for crimping-as may the drawing itself. Heating the second set of rolls at least sufficiently to prevent the drawn strand from cooling in the interim (however brief) is conducive to a steady and high degree of crimping. Although not illustrated, methods and means for heating these rolls, preferably internally, will come readily to the mind of a person skilled in the art; e.g., circulation of heated fluid therein, or by electrical means as disclosed in my U.S. Patent 3,111,740. The herein illustrated arrangement f three rolls in each set, with their axes in a common plane, two of the rolls flanking and being contiguous with the other roll is a preferred arrangement, but it is not imperative for the practice of this invention, as will be apparent hereinafter.

FIGS. 4, 5, and 6 show, in front and side elevation and sectional plan, respectively, stufi'er-crimper 41 useful according to this invention. Rolls 31, 32, and 33 are shown incorporated in this apparatus, the latter two functioning also as stufiing feed rolls. The supporting frame comprises base plate 42, front plate 43, back plate 44, and top plate 45, all secured together by suitable means (not shown). Upstanding facade 46 is secured similarly to the front plate. Tubular stuffing chamber 50, which is nearly square in cross-section, is held in place against the front of the facade by four washers 51 overlapping the side edges of the front of the chamber and supported on four wing screws 52 threaded into suitable apertures in the facade. The front wall of the chamber overlaps portions of rolls 32 and 33, and the rear wall does likewise, down to the roll nip, while the side walls terminate adjacent the rolls, thereby forming a close-fitting entrance to the chamber for strand stuffed thereinto by the rolls. The upper end of the chamber is covered by cap 55, which has ears 56 overlapping the front and back walls of the chamber and pivoted thereto by pintles 57. Extension springs 59 stretched from pins 58 on the cap to pins 60 on the chamber walls bias the cap closed against the otherwise open top of the chamber.

Motor 61 afiixed to the top surface of the top plate 45 has shaft 63 extending to the rear through journal 62 upstanding from and secured by bolts 67 to the rear fac of back plate 44. Afiixed to the end of the motor shaft is pulley 64 interconnected by belt 65 to pulley 66 on the end of shaft 73, which carries roll 33 at its front end and extends through the front and back plates and also carries gear 69. Meshing with this gear is gear 68 on the end of shaft 72, the other end of which carries roll 32. Stub shaft 71 journaled in front plate 43 carries roll 31.

Located below rolls 32 and 33 are several components not being used as stutfer-crimper 41 is shown in FIGS. 4, 5, and 6. They are guide block 75, affixed to the facade by screw 76, and overlying guide clip 77, which is secured to the guide block by bolt 78 at the side. Both the guide block and clip extend arcuately toward the nip of the rolls. Use of these guide elements (and non-use of roll 31) appears in the embodiments shown in FIGS. 7 and 8, which are described hereinafter.

In the embodiment already described, strand 20 is attenuated to become strand 20' in the drawing zone between first set of rolls 21, 22, 23 and faster running second set of rolls 31, 32, 33, the strand passing in essentially nonslipping contact with the rolls in each group. Immediately after having been drawn to increased length and thereby molecularly oriented, strand 20 is fed upward through the nip of rolls 32 and 33 and thus stuffed into the entrance of chamber 50. Although the surface speed of the rolls feeding the strand into the crimper is the same as the speed at which the strand leaves the drawing zone, i.e., neither an overfeed nor an underfeed according to roll speed, the tendency of the recently drawn strand to retract in length produces in effect an underfeed, be it ever so slight, to the crimping chamber. The chamber itself is filled with accumulation 20 of crimped strand, shown (stylized, for clarity) in FIG. 4 by a cutting away of part of the front wall of the chamber, and is otherwise unheated and may be positively cooled (e.g., by circulation of a coolantn0t shown'between the exterior and interior walls thereof) as in my US. Pat. 3,111,740.

Because the stuffing chamber is always full during crimping operations each straight-length increment of strand entering the chamber is compressed axially (i.e., longitudinally) and is forced to buckle, much as an overloaded structural column buckles. Continual buckling of successive length increments at the chamber entrance produces a crimping of the strand. Of course, the continued stuffing of the strand into the chamber forces the terminal part of the strand accumulation therein to emerge gradually therefrom between the spring-loaded cap and the upper end of the chamber. Emergent crimped strand 20' is in relaxed condition and is wound up onto cone 27 driven by contact (through the layers of strand on it) with drive roll 80.

FIG. 9 shows, from the side, a short length of unoriented (or only partly oriented) monofilament strand 20. In transverse cross-section it is round, although that is not essential. FIG. 10 shows a like amount of strand 20', attenuated to increased length and thereby oriented. FIG. 11 shows the same length increment of strand 20' at an early stage of buckling under axially compressive stress. FIG. 12 shows the same length increment, now designated 20", completely buckled into a generally U-shaped configuration such as exists inside the confining chamber. FIG. 13 shows, on a much smaller scale, a longer length of strand 20", including several buckled length increments, showing the generally curved arms of the U-shaped configurations (or crimps) stylized to the extent of being shown apart or separated although in the chamber there is little or no such separation. FIG. 14 shows, on an even smaller scale, relaxed crimped strand 20" such as is produced according to this invention.

Although the drawings illustrate only a monofilament strand, it will be understood that the term strand as used herein includes also a multifilament strand and that shorter lengths (e.g., staple) than usually termed continuous may be present. Suitable strand compositions will come readily to the mind of a person skilled in the textile arts. Prominent among the suitable compositions are the nylons (polycarbonamides), e.g., 66-nylon (i.e., polyhexarnethylene adipamide), also 6-nylon, ll-nylon, 610-nylon, and fiber-forming copolymers thereof, including terpolymers. Other suitable polymeric materials for strands to be treated according to this invention include most of the thermoplastic fiber-forming materials, such as polyhydrocarbons (e.g., polyethylene, polypropylene), polyesters (e.g., polyethylene terephthalate), polyacrylonitrile and copolymers of arcrylonitrile with other vinyl compounds, also copolymers of vinyl chloride and vinylidene chloride, and polyurethanes. This list is simply exemplary and is not intended to be exhaustive of suitable compositions, most or all of which are thermoplastic.

If a heated draw pin is used the appropriate temperature for it will depend upon the characteristics of the strand composition and the speed of the strand over the drawn pin. Appropriate processing speeds lie in the range of from one hundred to one thousand yards per minute (y.p.m.), but somewhat slower or faster speeds may be employed. For 66-nylon at an input of 100 y.p.m. and output of 400 y.p.m. (draw of 4 the draw pin temperature may conveniently be between 150 and 250 C. The speed at which the strand is fed into the stuffer-crimper correlates with the output speed from the drawing zone, of course, and the roll temperature preferably prevents the strand from cooling before entering the crimper, which itself is preferably constructed to maintain the strand temperature so long as the strand is under crimping compression, asin my US. Patent 3,348,283 and patent application Ser. No. 650,762 filed July 3, 1967.

As previously indicated, because of the immediate succession of drawing and crimping steps and of the heat engendered therein preheating of the strand is not required for crimping according to this invention and may not be required for drawing. The moisture content of the strand, if appreciable, may have a deleterious effect upon the desired treatment or its results. In general, therefore, the strand should not be wet, the preferable content of water (and/or any lubricant or softening, swelling, or plasticizing agent or solvent, all of which may be collectively referred to as moisture) being less than about A strand at such low moisture content may be considered as essentially dry or moisture-free for the purpose of the present invention. The realtive humidity in and about the chamber should not exceed about 20% for the usual textile strand compositions, the upper limit of humidity varying somewhat according to the moisture content and sensitivity of the composition.

FIGS. 7 and 8 show (in front elevation, but rotated 90 clockwise) the crimper of FIGS. 4, 5, and 6 but with the strand passing therethrough being fed directly by and between rolls 32 and 33 in line with their common tangent (through the roll nip). Additional rolls ahead of rolls 32 and 33 may prove useful in attaining essentially non-slipping contact at a pressure that will not damag the strand. Thus, in FIG. 7, added pair of nip rolls 82 and 83 are so located, and strand 20' passes therebetween. the rate of strand travel in such intervening portion of the strand path may be substantially the same as at the end of the drawing zone; it should not be less and may be more, thereby tensioning the strand further and, if desired, actually drawing it further. This enhanced under feed is accomplished by regulating the surface speeds of the various sets of rolls in any suitable manner, which may be conventional in itself, so that rolls 82, 83 have a speed intermediate that of slower rolls 21, 22, 23 at the beginning of the drawing zone and faster rolls 32, 33 at the crimper input. The latter rolls may run anywhere from several percent to perhaps ten percent, or somewhat more, faster than rolls 82, 83 while merely tensioning the strand, which was already drawn to increased length between rolls 21, 22, 23 and rolls 82, 83. However, at greater degrees of overspeed the strand probably will be drawn to further increased length unless a maximum draw for the particular strand composition already had been imposed, and may equal or even exceed the previous draw if desired. It is preferred, although not necessary, that the strand not have been drawn significantly at a remote previous time, although appreciable benefit from the present invention may be attained if such previous draw did not exceed about half the total drawability of the undrawn strand, thereby leaving it still substantially drawable.

When operating upon strands made of either 6 or 66 nylon it is customary to employ a total draw of about 4X, i.e., a total drawing underfeed of 400% increase in strand length, although higher draw ratios may be employed. It is preferred to limit the degree of underfeed from rolls 82, 83 to the crimper to at most half the total drawing underfeed, or in such instance to not much more than about 200%. A range of from about 5 to 50% underfeed is preferred when little or no added draw is desired, and a range of from about to 200% when substantial added draw is desired at the crimper input.

FIG. 8 also shows the same stulfer crimper with straight-in feed of the strand into the stufling chamber but without added intermediate rolls 82, 83. In both FIGS. 7 and 8 the strand passes between guide block 75 and overlying clip 77 to center it along the nip of rolls 32 and 33. When using all three rolls, as in FIGS. 4 to 6, it may be desirable to locate a pigtail or other guide ahead of the first roll and centered from end to end thereof for a like purpose.

Other variations in or modifications of the described apparatus and process may be made without involving a departure from the inventive concept. Any similarly useful compressive crimping device may replace the illustrated stuffer-crimper, which is merely exemplary, as is the spring-loaded cap as the device for applying backpressure to the strand accumulation in the crimper. Such a crimper may have a stuffing chamber with a round bore and a plunger therein as the back-pressure element, for example. Also useful is a stuffer-crimper having a frictionally retarded back-pressure device of wheel-like or gear-like configuration, as disclosed in US. Patent 3,027,619. Bore-impeding back-pressure elements may be eliminated by use of such stutter crimper as is illustrated and described in my U.S. Patent 3,279,025. Each stuifer crimper has a chamber of sufiicient dimensions that the crimped strand, however heated, is retained therein for a sufiicient time for the crimps to be set thereby with or without positive cooling. Expect when using the last mentioned type of stuffer crimper, windup of the crimped yarn expelled from the chamber preferably should be synchronized to accommodate the yarn so expelled without, however, withdrawing yarn from ahead of the backpressure devise; the portion of the cap covering the chamber illustrated herein may be used to control the windup rate, or a sensing device inside the chamber, such as disclosed in my US. Patent 3,280,444, which is well adapted to use with a stutter-crimper of the type disclosed in US- Patent 3,027,619, may be employed.

Strands crimped according to the present invention are characterized by excellent crimp stability, despite absence of conventional strain-relieving features, which have been customary despite the complication and expense attendant thereon. Control of the travelling strands, especially at high rates of travel, such as in the vicinity of a thousand yards per minute, is comparable to that obtainable with overfed strands at lower rates, such as several hundred yards per minute. Other benefits and advantages of this invention, which produces crimped textile strands of exceptional bulk, will become apparent and accrue to those who undertake to practice it.

The claimed invention:

1. In treatment of a textile strand to enhance its bulk, wherein it is drawn in a drawing zone and then promptly crimped in a crimping zone, the improvement comprising underfeeding the textile strand from the drawing zone to the crimping zone and thereby tensioning the strand.

2. Strand treatment according to claim 1, wherein the degree of underfeed is sufficient to draw the strand to increased length.

3. Strand treatment according to claim 2, wherein the degree of underfeed is from about 100 to 400 percent.

4. Strand treatment according to claim 1, wherein the degree of underfeed is suflicient to elongate the strand reversibly.

5. Strand treatment according to claim 4, wherein the degree of underfeed is from about to 50 percent.

6. Treatment of a drawable textile strand to enhance its bulk, comprising drawing the strand to increased length in a drawing zone and then feeding the drawn strand to a crimping zone under tension and compressively crimping the drawn strand in the crimping zone.

7. Strand treatment according to claim 6, wherein the strand is drawn to increased length in a plurality of stages in the drawing zone and the last of such stages is contiguous with the crimping zone.

8. Strand treatment according to claim ,7, wherein the degree of draw in the last stage of the drawing zone is from about 100 to 200 percent.

9. Strand treatment according to claim 6, wherein a tensioning stage in which the strand is stretched substantially reversibly intervenes between the drawing zone and the crimping zone and is contiguous with both.

10. Strand treatment according to claim 9, wherein the strand elongates from about 5 to percent in the tensioning stage.

11. Continuous draw-crimping process for textile strands, comprising tensioning a textile strand sufficiently to draw it to increased length, maintaining the drawn strand under tension until crimping it, and stutter-crimping the resulting strand.

12. Draw-crimping process according to claim 11, wherein the strand is subjected to longitudinally compressive stress immediately upon removal of tensioning stress.

References Cited UNITED STATES PATENTS 2,419,320 4/1947 Lohrke 28-72 2,686,339 8/1954 Holt 28-72 2,917,806 12/1959 Spence et al. 19-66 3,111,740 11/1963 Stanley 28-1 3,167,846 2/1965 IWnicki et al 28-1 3,177,556 4/1965 Van Blerk 28-1 LOUIS K. RIMRODT, Primary Examiner 

